Method of treating ferrotitanium ores



Patented lFeb. 4, 1930 UNITED STATES PATENT OFFICE` GEORGE J'. BANCRO'FL OF DENVER, `COLORADO METHOD OF TBEATING FEBBOTITANIUM OBES y vApplication led February 19, 1929. Seria1No.'341,205.

bi'ned with titanium and which usually con-` sist of a mixture of magnetite (Fe304) or/and hematite (FeaOa) with titanium` iron compounds of variablecomposition and of earthy materials. Among the titaniumiron compounds are ilmenite (FeTiOS), ti-

tanite (CaTiSiO5) and a large number of other. compounds whose titanium content variesy from 5.6% to 69.5%. Among the earthy materials, quartz, lime, spinel, mica and olivine are' the most common.

Iron and titanium oxide (TOZ) ,are both valuable by themselves, but mixtures of the two are of little or no value because the titanium oxide is very refractory and nonreducible and makes noniuid slags at the usual temperatures employed with ironsmelters. It is the object of this invention to produce a method whereby the iron and the titaniferous and other nonferrous materials of ferrotitaniferous ores may be separated in such a way that these ores may be treated in a commercial way and at a moderate cost.

The method by means of which I accom.-

.plished the results desired is as follows:

The ore is first crushed and then ground to suitable lineness for the purpose of unlocking the mineral aggregates fromeach other without breaking down thel crystals as such.

To the crushedy and ground orei ispnowv added pulverized iluorspar (calcium fluorid) and the two thoroughly mixed.

The mixture of ground ore and luorspar is now subjected to a reducing roast, preferably in an apparatus comprlsing a. revolving, inclined cylinder having a. of re- `ractory material. Hot ases from a mace together with. some un urned gas suchv as carbon monoxide are 'introduced into theI lower end of the rotary kiln and the pulverized ore and iiuorspar' mlxed with coal dust or oil residuum is introduced into vthe upper? u Aend of the kiln. As the kiln revolves :the ore mixture travels slowly towards the lower-or discharge end. Thetemperature at which the reducing raast is carriedout is suchlthat .exceptionally strong chemical atinity of ti:-

tanium for oxygen. Iron oxides are'easily reduced and iron compounded with titamum and oxygen can be torn or unlocked from the combination at attainable Vtemperatures when lthe -reducing roast is carried out in the presence of uorspar which is therefore mixed with the ores as above described.

After the mixture of `ferrotitaniferous ores and iuorspar has passed through the furnace where it has been subjected to a reducing roast, it is necessary to guard against reoxidation and therefore the white hot pulp as it leaves the kilny or furnace is passedl through li-ve steam and into water.

In passing throughA1 the furnace the particles of iron oxide are reduced to small iron Sponges which the high temperature near the discharge end coalesces into small iron nuggets. The titanium-iron oxides are reduced more or less depending on the size of .the particles and the percentage of titanium. f Some particles become little honeycombs of class are therefore reduced to a less extent`- than the smaller particles. The high temperature at the finish of the roast coalesces the reduced iron and exudes more or less of the enclosed titanium oxide, some of which is in such a fine state of subdivision that it passes oi with the gas and is caught in the flue dust chambers, together vwith other fumes such as carbon black and calcium fluo-tiltanate. This titanium is` now' ready for the market as a dark palntplgment.

The pulverized fluorspar which is mixed with the ore before the latter is roasted tends to promote separationof the iron and titanium. The action of the luorspar may be partly catalytic or it may be due to breaking u the titanium carbides, carb'onitrides and mtrides.

ovfing to the 'speen anni@ o; page@ alkali.

used less nitrides are found in the calcine's and the iron concentrates contain less tita nium.

The exact action that takes place when luor'spar is present in the ore during the roasting operation is not known, but it is believed that some calciumdiuo-titanate is formed and distils over into the flue cham;

bers and that it also decomposes the nitrides,

carbonitrides and carbides. The amount of luorspar to be used varies with the nature of the ores to be treated; the location and the commercial conditions. In no case, how- '.vver, should more iuorspar be used than isv required toform calciuni-iit1otitanate with all of the titanium present in the ore. -The fluorine does not combine with the iron to any appreciable extent unless used in ex' cess. y

The water into which the incandescent pulp is dropped should be limited in quantity and should contain a small amount of caustic By using a small or limited supply of water, it will be maintained at the boiling point so that a largeamount of steam' will be generated. The discharge vend of the rotary kiln must be connected with the water container or tank by means of a chamber of considerable height so that the incandescent materials will be exposed to the steam for an appreciable length of time before it strikes the water and it should also be spread as widely as possible before striking the Waterso as to prevent piling up and so as to obtain uniform cooling. By passing the incandescent pulp through steam and into water, the carbonitrides and nitrides are broken up and yield ammonia which' is a valuable byproduct.

The material that has passed through the roaster and which has been cooled in the water consists of a mixture comprising small i iron nuggets vesicular iron shells containing entangled titanium oxide, thin shells of iron surrounding unreduced centersof high grade titanium oxide and some uorspar compounds. The iron is tough and malleable while the unreduced compounds such as tita-` nium oxide and its unreduced compounds are brittlel and friable.

purpose a crusher is crushing however. In 'order to effect the desired separation, the iron particles and nuggets should remain as they are while the unreduced rock crystals should be pulverized and reduced to extreme fineness. The type of grinder that is best suited for the selec'- tive crushing that is necessary for the purpose here under consideration is known as an impact rinder in which the materials are thrown y the action of centrifugal force against a hard wall or other surface. The brittle particles are crushed by their own momentum when theyr strike t-he wall, but the malleable and tough iron particles are not broken .fup to the same extent, thereby obtaining av selective grinding. Aggregates formed in part of iron and in part of crystals are broken apart due to their greatly different degrees of hardness and britt-leness and therefore the iron cells have a good chance of separating from the more brittle titanium compounds.

After the materials have been run through an impact grinder, they are then screened, whereby the coarse iron nuggets are separated from the smaller particles.

The parts that pass through the screen are concentrated by any ordinary wet concentration method as, for example, by a Wiliey. table and the very line materials are subjected to a flotation separation.

y The concentrates will not be pure iron nor willthe tailings bevpure titanium oxide but the products are in commercial'form. The

iron, while the tailings and the titanium flue dust are high grade titanium products. The

flue dust having been formed by sublimation is, of course, very fine and is particuarly Well suited for pigments.

The fumes from the furnace are caught in the roasting chambers as above explained.

When the incandescent materials pass from thefurnace and into the steam, the nitrides are broken up and form ammonia which becomes a valuable byproduct.

The tailings from the concentrator are richk in titanium and are ready for the market or for the rener while the iron may be marketed or sent to the furnace.

In the accompanying drawing the sequence and relationship vof these'veral steps are.

shown.A It is well knownthat Aelectric smelting of ores on account of its high temperature enables better and different results to be obtained than when the smelting is accomplished by means of heat obtained from the combustion of coal, but the expense attendant upon electric smelting makes this process, as

a rule prohibitive. The greatest consumption of electric 'energy during the smelting takes place in raising the temperature of the ore to the peint that can be reached'by 'means which has herein been described, it is possible to transfer the ore directly from the rotary kiln to an electric furnace insteadof passing it into the water-in the manner above described. In this way the greater amount of heat is produced by the cheaper method and the electric furnace is used merely to raise the ytemperature of the ore from the p' int attained in the rotary kiln to the temperature desired to be obtained in the electric furnace and by this means the same results are obtained as if the entire amount of heat were obtained' by electric me'ans with only a small l part of the cost which would be necessary if the temperature were raised by electric means entirely. i

I have found that the fluorspar performs its function of producing an almost complete separation ofthe iron fromthe titanium when the ore is passed through an electric smelter as when the process above described is em-' ployed.. By combining the two dierent methods of obtaining the necessary temperatures the desired results are obtained at a reasonable figure even when an electric smeltnium and eart l mixture to a reducing roast.

3. The method of treating ferrotitanium ores so as to separate the iron-from the tita- ,nium and earthy matters which consists in crushing and then line grinding the ore, mixin ulverized luorspar with the ground ore, l su ]ect ing the mixture to a reducing roast phere, passing the incandescent material from the roastlng furnace through steam and into water, regrinding the roasted ores in an impact grinder whereby the brittle nonferrous particles are further reduced in size, subjecting the ground material to a screening process whereb the larger iron particles are separated, an subjecting the particles that pass-through the screen to the action of a concentrator whereby the smaller iron particles are separated from the nonferrous materials.

6. The method of treating ferrotitanium ores so as to separate the iron from the ltitanium and earthy matters which 'consists in crushing the ore, grinding the crushed ore, mixing the ground ore with pulverized iluorspar and carbonaceous material, subjecting the mixture to a roast in a reducing atmosphere, passing` the incandescent material from the roasting furnace through steam and into water containing a caustic alkali regrinding the roasted ore in an impact grinder whereby the brittle nonferrous particles are further reduced in size, subjecting the ground material to a screening action wherebythe larger iron particles are separated from the smaller and then concentrating the screenings for the purposev of e'ecting'a further separation of the ferrous from the nonferrous materials. I

In testimony whereof I arixmy signature.

' GEORGE J. BANCROFT.

and passing the roasted material through steam and into water. y

The method of treating ferrotitanium ores so as to .separate the iron from the titay matters which consists in lcrushing and-'then fine grinding the ore, mixing pulverized fluorspar with the ground ore,

subjecting the mixture to a reducing' roast, y

passing the roasted material through steam and into water and regrinding the ore in an impact grinder whereby the more brittle particles'will be further reduced while the iron.

particles are left unbroken.

nov

crushing the ore, grinding the crushed ore, mixlng the ground ore with pulyeriggd iiuorspar and carbonaceous' material, subjecting the mlxture -to a roast in a reducing atmos- 

